For subscribers or users in radio networks, such as cellular networks or mobile telephone systems, satellite networks or local area networks, etc., the most important part is the mobile station. In order to meet the requirements from the subscribers, the mobile station has to be small and compact enabling the user to carry and store the unit virtually anywhere.
For example, for usage in mobile telephone systems there are many different types of mobile telephones on the market, both with and without a foldable housing and with and without a movable antenna. Generally, a mobile telephone has a housing provided with an earpiece, a microphone, a display, and a keypad on the front and an antenna arranged on the top. The keypad has numbered buttons for dialing as well as buttons for different kinds of functions such as on/off, send, volume control, and buttons for answering SMS (Short Message Services, transmission of short text messages for presentation on the display), etc.
Further, mobile telephones are provided with indicators for different kinds of status information, such as a low battery indicator and an indicator showing whether the phone has established contact or not with a base station. The latter indicator is required on mobile telephones connected to most common mobile telephone systems based on the cellular architecture.
Cellular architecture or cellular network is a technique that involves subdivison of a service area into a number of small cells to facilitate frequency reuse and an increased number of subscribers in the future. The mobile telephone interface to the cellular network is a base station, usually located in the center of a cell. In order to establish or maintain a call between two subscribers in a cellular network, the mobile telephone has to be in contact with the base station. As each cell has a limited area, the mobile telephone has to be in contact with different base stations if it is moved out from one cell area to another. It is important for the subscriber to know if the mobile telephone has established contact with any base station, when he intends to establish a call. This information may be presented on the display or a specific indicator on the phone.
EP-A-661 823 describes a portable communication apparatus including an upper casing 1a and a lower casing 1b which are rotatably connected to each other. When the apparatus is folded, so that the upper casing 1a overlays the front surface of the casing 1b, minimum necessary keys on the lower casing remain exposed to the outside. The power key 9 is provided on the top of the upper casing 1a to prevent the user from operating the power key 9 by accident when the apparatus is folded.
JP-A-7-203526 shows a portable phone with a "singing stop key" SW2 provided at the top of the unfolded telephone. The position of the key, which stops the incoming call alarm, is different from the position of the other keys for enabling it to be operated even when a call comes in while the telephone is in a pocket or a bag.
Other well-known mobile telephones are provided with usually one status indicator on the top of its housing.
However, the above-mentioned prior art mobile radio stations and mobile telephones often have either an indicator or a button provided on the top of the telephone housing to enable certain functions and information to the subscriber even when the telephone (if it is foldable) is folded or when the telephone is in a passive state, often situated in a pocket or a bag. Since the top area of the housing gets smaller and smaller as the mobile telephones become smaller and smaller, the area on which externally arranged indicators and buttons can be provided is limited. Consequently, only a few indicators and buttons with just a few functions are available on top of the casing of currently produced mobile telephones.